Glass-forming tendency in the GeS_x system

Abstract

Method of preparation of bulk glassy samples in the GeS (x=1–2) system by cooling (quenching) from the melt in water (with the rate of cooling of the order of 10² °C/sec) is described. Initial substances were of 6–7N purity. Characteristic temperatures of phase transitionsT _g (glass transition),T _k (crystallization) andT _m (melting) were determined using DTA. Glass-forming tendency was evaluated by means of the relationT _k —T _g/T_m —T _k that was previously proposed by the author. It is found that glass can formed for compositions from GeS_1.1 upwards, the minimum in the glass-forming tendency being in the vicinity of GeS_1.0. Glasses in the whole range of compositions investigated consist of several phases, in accordance with the equilibrium diagram of Ge-S alloys. It is suggested to divide these glasses into three groups:

• 1. GeS-GeS_1.12, which are formed hardly, are composed prevalently from GeS and small quantities of GeS₂ and G,

• 2. GeS_1.12-GeS₂, which are formed more easily, are composed from GeS and GeS₂ (increasing GeS₂ content),

• 3. from GeS₂ upwards, which are formed very easily, are composed from GeS₂ and sulphur.